Balloon-printing machines are known in which a rotary printing cylinder is used. U.S. Pat. No. 3,868,899 to Norman H. Nye et a1. dated Mar. 4, 1975 describes such a machine. However, it is well known such printing cylinders cannot produce on the balloon an image or pattern which has precise contours and in which the printed areas have an ink layer of constant thickness. Therefore, the quality of the image is rather poor. It is known that a good quality image can be printed on a balloon only by using the silk-screen printing process, in which the ink is squeezed through the interstices of a flat woven sheet of silk or the like. Up to now, printing balloons with silk-screen printing press were largely a manual operation and, consequently, very slow and a very low productivity.